Formula
How this estimate works
rectangle = length x width; triangle = base x height / 2; circle = pi x radius squared
A 12 ft by 10 ft room is 120 sq ft; add separate shapes for closets, offsets, or irregular areas.
Worked example
Measure two rooms before ordering flooring
For rooms or yards that are not a single rectangle, the calculator lets you add multiple simple areas and total them before applying material waste separately.
- Measure each room section in feet and enter each rectangle as a separate area.
- Use triangle or circle shapes for angled corners, bay areas, or round sections when needed.
- Keep the measured square footage separate from flooring waste, paint coats, or product coverage rules.
How to calculate square footage
For a rectangle, multiply length by width. For a triangle, multiply base by height and divide by 2. For a circle, square the radius and multiply by pi.
Use square footage for material estimates
Square footage is the first step for paint, drywall, flooring, mulch, gravel, pavers, and many other home project estimates.
Common estimating mistakes
- Measuring in inches but entering the values as feet.
- Treating an irregular room as one large rectangle and over-counting unusable space.
- Using square footage as a final order quantity without product-specific waste, roll width, or coverage limits.
Assumptions used
- Each shape can be multiplied by quantity.
- Square yards are calculated by dividing square feet by 9.
- Square meters are converted from square feet for planning.
Before you order materials
- Break irregular spaces into simple shapes.
- Measure each room or section separately.
- Use the final square footage as the starting point for material calculators.
Frequently asked questions
How do I calculate an irregular room?
Break the room into rectangles, triangles, or circles, calculate each area, and add them together.
How many square feet are in a square yard?
One square yard equals 9 square feet. Use this conversion when flooring, turf, carpet, or fabric is priced by square yard instead of square foot.
Can I include multiple rooms?
Yes. Use the multi-area rows to add each room or project area.